Recently, interest in chemical and biological sensors using nanostructures (e.g., carbon nanotubes) sensitive to ambient environment has increased, and various types of sensors based on the nanostructures have been proposed.
A conventional nanostructure sensor has been disclosed in “B. L. Allen, P. D. Kichambare, A. Star, “Carbon Nanotube Field-Effect-Transistor-Based Biosensors,” Adv. Mater. Vol. 19, pp. 1439-1451, 2007.” The paper discloses a technique of sensing a specific DNA by attaching a thiolated single-stranded DNA (hereinafter, referred to as an ssDNA) to a nanostructure sensor and measuring a change in electric conductivity generated when hybridizing a complementary ssDNA using the ssDNA as a probe. The DNA sensing technique proposed in the prior literature is a method of sensing a change in electric conductivity based on the hybridization between the probe ssDNA and the complementary ssDNA, performed on an electrode (e.g., gold (Au)).